Well the year is 2012 and you must use microdata, there is a microdata module for drupal 7, but if you are still at drupal 6 you will need to customize. I have been using vote up/down module for my ratings so I needed to change template file of the module to add this microformats to node display so I added this code at the end of widget.tpl.php
<?php
// Output of microdata snnipet for ratings
$node=node_load($content_id);
$title = $node->title;
?>
<div itemscope itemtype="http://data-vocabulary.org/Review-aggregate" id="GameRatingInfo">
<span itemprop="itemreviewed"><?php print $title;?></span>
<span itemprop="rating" itemscope itemtype="http://data-vocabulary.org/Rating">
<span itemprop="average"><?php $total_points=$up_points+$down_points; $result=round((($up_points+1)/($total_points)*5),2); print drupal_convert_to_utf8('Prosje?na ocjena: ', "ISO-8859-2").$result;?></span>
od <span itemprop="best">5</span>,
</span>
Broj glasova<span itemprop="votes"> <?php print $total_points;?></span>.
</div>